(R 2.9.2 on Windows XP)
Turns out that
my.data.frame[c(1,3)] <- list(NULL, NULL)
and
my.data.frame[c(3,1)] <- list(NULL, NULL)
are not the same. Is this expected?
Example:
d0 <- structure(list(Year = c(2009L, 2009L, 2009L), Season = c(1L,
1L, 1L), Series = c(1L, 1L, 1L), Mst = structure(c(1L,
1L, 1L), .Label = "", class = "factor"), Yield = structure(c(1L,
1L, 1L), .Label = "", class = "factor")), .Names = c("Year",
"Season", "Series", "Mst", "Yield"), row.names = c(NA,
3L), class = "data.frame")
d1 <- d0
d1[c(3,1)] <- list(1:3, 4:6)
print(d1)
Year Season Series Mst Yield
1 4 1 1
2 5 1 2
3 6 1 3
d1[c(3,1)] <- list(NULL, NULL)
print(d1)
Season Series Yield
1 1 1
2 1 2
3 1 3
It appears that the above assignment deletes column 1 from the data frame,
then sequentially deletes column 3 (Mst, which was originally column 4
before column 1 was deleted).
Compare this to
d1 <- d0
d1[c(1,3)] <- list(NULL, NULL)
print(d1)
Season Mst Yield
1 1
2 1
3 1
Kevin Wright
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